PubMed Health⌕ Search

PubMed · 15876826

Extracorporeal sensing techniques.

Abstract

Many physiologic variables have been measured in the extracorporeal circulation by experimental systems but only a few systems have reached technical maturity for everyday application. Variables relating to cardiovascular function, which today can be measured in the extracorporeal system, are pressure, temperature, and measures of blood composition such as hematocrit, hemoglobin, and total protein concentration. While the measurement of blood composition and temperature is well established, and while the use of extracorporeal pressure information awaits further analysis for robust application, recent interest focused on continuous measurement of plasma sodium concentration which is believed to be of major importance for optimal blood treatment. However, problems with a simple, reliable, and continuous measurement of plasma sodium for everyday use have not yet been resolved. As can be seen from the growing interest in isothermic or isonatremic treatment modes which turns away from constant and profiled treatment modes without feedback control, the treatment goal is now to provide stable conditions within the patient so as to minimize interference with intrinsic physiological control mechanisms. This, however, requires valid and reliable measurement of the specific patient variables of interest.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Daniel Schneditz. 2005. Extracorporeal sensing techniques.. https://doi.org/10.1159/000085421

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Mathematical model describing erythrocyte sedimentation rate. Implications for blood viscosity changes in traumatic shock and crush syndrome.

BACKGROUND: The erythrocyte sedimentation rate (ESR) is a simple and inexpensive laboratory test, which is widespread in clinical practice, for assessing the inflammatory or acute response. This work addresses the theoretical and experimental investigation of sedimentation a single and multiple particles in homogeneous and heterogeneous (multiphase) medium, as it relates to their internal structure (aggregation of solid or deformed particles). METHODS: The equation system has been solved numerically. To choose finite analogs of derivatives we used the schemes of directional differences. RESULTS: (1) Our model takes into account the influence of the vessel wall on group aggregation of particles in tubes as well as the effects of rotation of particles, the constraint coefficient, and viscosity of a mixture as a function of the volume fraction. (2) This model can describe ESR as a function of the velocity of adhesion of erythrocytes; (3) Determination of the ESR is best conducted at certain time intervals, i.e. in a series of periods not exceeding 5 minutes each; (4) Differential diagnosis of various diseases by means of ESR should be performed using the aforementioned timed measurement of ESR; (5) An increase in blood viscosity during trauma results from an increase in rouleaux formation and the time-course method of ESR will be useful in patients with trauma, in particular, with traumatic shock and crush syndrome. CONCLUSION: The mathematical model created in this study used the most fundamental differential equations that have ever been derived to estimate ESR. It may further our understanding of its complex mechanism.

Blood Physiological Phenomena↗

In preeclampsia, the circulating factors capable of altering in vitro endothelial function precede clinical disease.

The pathophysiology of preeclampsia involves the release of a circulating factor(s) from a hypoperfused placenta that activates the maternal endothelium. This study investigated the effect on in vitro endothelial function of plasma taken from women in whom preeclampsia subsequently developed. Women at increased risk for an adverse pregnancy outcome were identified using Doppler waveform analysis. Plasma samples (22 and 26 weeks) were incubated with myometrial vessels taken from women with uncomplicated pregnancies. Wire myography was used to study the effect of plasma on the endothelium-dependent vessel behavior. Incubation of vessels from normal pregnant women with plasma from women in whom preeclampsia subsequently developed (n=19) significantly reduced endothelium-dependent relaxation, compared with vessels incubated with plasma from normal pregnant women (n=48). This effect was demonstrable for plasma taken at 22 weeks (residual constriction 47.1+/-6.6% versus 32.0+/-4.4%, P=0.004 at 1-hour incubation; and 59.1+/-8.4% versus 42.3+/-5.9%, P=0.001 at 18-hour incubation) and 26 weeks (59.2+/-5.2% versus 29.1+/-5.6%, P<0.001 at 1 hour; and 63.3+/-7.6% versus 31.9 +/-7.2%, P<0.0001 at 18 hours). Endothelial-dependent relaxation was unaltered after incubation with plasma taken from women in whom normotensive intrauterine growth restriction subsequently developed (n=19). This study supports the hypothesis that plasma, from women in whom preeclampsia develops, collected weeks before diagnosis is capable of altering endothelial function.

Blood Physiological Phenomena↗